1. Field of the Invention
This invention relates to certain 3-substituted-benz[d]isothiazole-1,1-dioxides, and in particular, it relates to 3-(carbocyclic aryl)-benz[d]isothiazole-1,1-dioxides wherein the carbocyclic aryl group is substituted in the para position with an N-heterocyclic moiety.
2. Description of the Prior Art
Though various 3-substituted-benz[d]isothiazole-1,1-dioxides have been disclosed, only a few 3-aryl derivatives are known. P. Fritsch, Ber., 29, p. 2290 (1896) reported that the 3-phenyl derivative was obtained by the reaction of 3-chlorobenz[d]isothiazole-1,1-dioxide (saccharin pseudo-chloride) and benzene under Friedel-Crafts conditions. The 3-(p-dimethylaminophenyl) derivative was prepared similarly. The 3-(p-chlorophenyl) derivative was obtained by the treatment of ammonium 2-(4'-chlorobenzoyl)benzenesulfonate with phosphorus pentachloride as reported by Z. Horii, Jap. Patents Nos. 10,131/1964 and 8832/1964. R. A. Abramovitch et al, J. Chem. Soc., Perkin Trans. I, 22, p. 2589 (1974) reported that the reaction of alkyl- and aryllithium compounds with 3-oxo-2,3-dihydrobenz[d]isothiazole-1,1-dioxide (saccharin) in tetrahydrofuran at -78.degree. C gave the corresponding 3-alkyl or 3-aryl derivatives exclusively and prepared the 3-phenyl, 3-(o-tolyl), 3-(p-methoxyphenyl) and 3-(2-pyridyl) derivatives in this manner. The latter authors also reported that the 3-phenyl derivative was prepared by the treatment of saccharin with two equivalents of phenylmagnesium bromide in tetrahydrofuran at ambient temperature.
Copending U.S. patent application Ser. No. 836,025 of Alan L. Borror, James W. Foley, Marcis M. Kampe and John W. Lee, Jr. filed concurrently herewith is directed to a method of synthesizing 3,3-disubstituted-2,3-dihydrobenz[d]isothiazole-1,1-dioxides possessing a carbonyl group in the 2-position. Depending upon the carbonyl group and the 3,3 substituents, the products of the synthesis may be employed as pH-sensitive indicator dyes, antihalo dyes or photographic optical filter agents. As disclosed and claimed therein, the method of preparing these compounds comprises reacting a 3-(phenyl/naphthyl)-benz[d]isothiazole-1,1-dioxide and a 4'-OP-phenyl/4'-OP-naphthyllithium compound to give the corresponding 3-(phenyl/naphthyl)-3-(4'-OP-1'-phenyl/4'-OP-1'-naphthyl)-2,3-dihydrobenz[ d]isothiazole-1,1-dioxide wherein P represents a protecting group compatible with organometallic reagents. The compound thus prepared is then reacted with the selected carboxylic acid halide to give the corresponding 2-carbonyl derivative which is then treated with acid to remove the protecting group and yield the product. The phenyl or naphthyl group of the 3-(phenyl/naphthyl)-benz[d]isothiazole- 1,1-dioxide employed in the initial step of the synthesis may be unsubstituted, or it may be substituted with, for example, an N-heterocyclic moiety and/or other substituents.
The present invention is concerned with certain 3-substituted-benz[d]isothiazole-1,1-dioxides useful as intermediates in the aforementioned synthesis.